1. Field of the Invention
The present invention relates to a novel compound of cerium (IV) and to a process for the preparation thereof. This invention more especially relates to a novel compound of cerium (IV) that is readily dispersed in water.
2. Description of the Prior Art
It is known to this art, from the Kirk-Othmer E.cyclopedia of Chemical Technology, 2nd edition, Vol. 4, p. 850, that a hydrated ceric dioxide of the formula CeO.sub.2.xH.sub.2 O may be prepared, wherein x is a number ranging from 0.5 to 2, in the form of a gelatinous precipitate by the addition of sodium or ammonium to solutions of ceric salts.
It has also been proposed to this art, according to French Patent No. 2,482,075, to prepare a cerium (IV) compound which is dispersible in water by dispersing an essentially dry hydrate of cerium (IV) oxide in an aqueous medium, the same having been subjected to a heat treatment at a temperature ranging from 200.degree. C. to 450.degree. C., in the presence of a disintegrating agent, in particular nitric acid. Heating in the presence of a disintegrating agent effects the disintegration of the aggregated crystallites into hydrated cerium (IV) oxide, thereby producing a dispersible cerium compound.
It is noted in this '075 patent that the preparation of a hydrate of cerium (IV) oxide may be carried out by precipitation beginning with a cerium salt; thus, for example, a high purity cerous carbonate may be dissolved in a nitric acid or hydrochloric acid solution to obtain a neutral solution of cerous nitrate or chloride, which is then oxidized with NH.sub.4 OH/H.sub.2 O.sub.2 to obtain the hydrate of cerium (IV) oxide.